Leading edge flap mechanism

ABSTRACT

An aircraft airfoil leading edge flap mechanism utilizing a pivotally mounted forming rib in combination with a portion of the airfoil skin having resilient characteristics. Extension of the rib by rotation about its pivotal mounting means deforms the resilient skin portion over the forming rib into a desired highly cambered, high lift, low speed airfoil curvature having increased area, camber and chord for landings and take-offs. An always smooth and uninterrupted airfoil nose section surface will be maintained at the retracted position during the extending or retracting movement and at the extended leading edge position.

United States Patent [1 1 [111 3,743,220 Stinson July 3, 1973 LEADINGEDGE FLAP MECHANISM Inventor: William E. Stlnson, Mercer Island,

Wash.

Assignee: Stinson Aircraft, Inc., Rentori.

Wash.

Filed: Oct. 26, 1971 App]. No.: 192,466

References Cited UNITED STATES PATENTS 4/1970 Cole et al 244/42 RCarhart et al 244/44 Primary Examiner-Milton Buchler AssistantExaminer-Carl A. Rutledge [5 7] ABSTRACT An aircraft airfoil leadingedge flap mechanism utilizing a pivotally mounted forming rib incombination with a portion of the airfoil skin having resilientcharacteristics. Extension of the rib by rotation about its pivotalmounting means deforms the resilient skin portion over the forming ribinto a desired highly cambered, high lift, low speed airfoil curvaturehaving increased area, camber and chord for landings and take-offs. Analways smooth and uninterrupted airfoil nose section surface will bemaintained at the retracted position during the extending or retractingmovement and at the extended leading edge position.

7 Claims, 2 Drawing Figures LEADING EDGE FLAP MECHANISM BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates to aleading edge flap mechanism in airfoils and in particular to a leadingedge flap utilizing a flexible skin for forming the desired cambercurvature.

2. Description of the Prior Art There have been many attempts to changethe contour of wings to provide high lift, low drag, low speed airfoilshape for landings and take-offs and yet be changeable back into a highspeed, contoured wing. Other devices which solve this problem in varyingdegrees are: Gilmore U.S. Pat. No. 1,631,259, June 7, I927; QuenzlerU.S. Pat. No. 3,089,666, May 14, 1963; Calderon U.S. Pat. No. 3,128,966,Apr. 14, 1964; Calderon U.S. Pat. No. 3,195,836, July 20, 1965; RiedlerU.S. Pat. No. 3.208,693, Sept. 28, 1965, and Cole et al U.S. Pat. No.3,504,870. Apr. 7, 1970.

None of these patents show the disclosed invention of a leading edgeflap that comprises a forming rib and an unattached flexible skinportion in a combined cooperating, structual arrangement andrelationship during extension of the flap only.

SUMMARY OF THE INVENTION Thus, a leading edge flap mechansim isdisclosed herein comprising a flexible skin, which when retracted formsthe nose and forward bottom surface of an airfoil, and a forming ribthat is contoured to a desired aerodynamic curvature for forming orshaping the flexible skin into a flap that in combination with theairfoil provides the required camber and chord configuration for highlift at low speeds.

A mechanism is employed which upon actuation moves the forming ribagainst the flexible skin portion and constrains the skin about thecurvature of the forming rib while simultaneously moving rotationallydownward and forward into the extended leading edge position.

The actuation of the mechanism is caused by rotationally driving means.The mechanism for extending and retracting the forming rib utilizes apair of linkages pivotally connected on a bellcrank which upon rotationplaces the linkages in an over-center locking position so that the flapupon extension is in a locked position and upon reverse rotation of thebellcrank the overcenter locked relationship becomes released and theforming rib retracted within the airfoil while the flexible skin isreturned to its previous condition of forming part of the high-speedairfoil.

In general, the present invention relates to an aircraft airfoil leadingedge flap mechanism comprising: a nose skin section of resilientmaterial forming part of the airfoil; a forming rib means pivotallymounted about a pivot means located within the airfoil adjacent itsleading edge, and an actuating means connected to the forming rib meansfor extending the forming rib means through rotation about the pivotmeans in a downward forward direction, and vice versa, whereby theforming rib means upon extending deforms the skin section into a desiredaerodynamic curvature for forming a highly cambered, high lift,low-speed airfoil.

In addition, it can be stated that the main aerodynamic features are:

1. Ability of the mechanism to achieve a well rounded leading edge orbulbous leading edge which has the effect of increasing wing camber andmaintaining lift at a higher angle of attack.

2. The device has, in comparison to a slotted L.E. flap, less drag for agiven amount of lift.

3. The device allows the additional feature of tailoring parts of thewing (by segmentation) to more or less degree than other parts, andstill retracting to a high speed configuration.

4. The device provides at all times during extension or retraction asmooth uninterrupted outer surface along the airfoil complete nosesection, upper and lower leading edge.

Accordingly, it is one of the most important objects to provide for aleading edge mechanism which in the retracted state, during extending orretracting movement and at the extended state or position, offers analways smooth curvature without interruptions over the airfoil noseleading edge area.

Also, a principal object of this invention is to provide a new methodfor providing the highest aerodynamic performance when converting a highcruise speed wing to a low speed wing for landings and take-offs.

Another principal object of this invention is to provide a flexibleleading edge flap for converting a high speed airfoil to a low speed,high lift, low drag airfoil.

A further object of this invention is to provide a flexible leading edgewing that is flexed from a retracted position against the wing leadingedge nose and lower surface to the desired or predeterminedaerodynamically curved shape in a position extended from the wingleading edge.

A still further object of this invention is to provide for a leadingedge flap mechanism utilizing a forming rib means which upon rotationfor flap extension, by an actuating means carrying a pair of linkagemeans, and which actuating means when driven by an associated drivemeans deforms a flexible skin portion of said airfoil into a desiredflap extended high camber, high lift curvature airfoil combination.

Another object of this invention is to provide a leading edge flaphaving an aerodynamically shaped flap nose unfoldable therefrom to givea wing capabilities of easy conversion from a high speed wing forcruising flight to a very high lift, low drag, low speed wing forlandings and take-offs.

Other objects and various advantages of the disclosed Aircraft LeadingEdge Flap Mechanism will be apparent from the following detaileddescription, together with the accompanying drawings, submitted forpurposes of illustration only and not intended to define the scope ofthe invention, reference being made for that purpose to the subjoinedclaims.

BRIEF DESCRIPTION OF DRAWINGS position illustrated in FIG. 1 with itsleading edge flap mechanism in extended position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention, the scope ofwhich is defined in the appended claims, is not limited in itsapplication to the details of construction and arrangement of partsshown and described, since the invention is capable of other embodimentsand of being practiced or carried out in various other ways. Also, it isto be understood that the phraseology or terminology employed herein isfor the purpose of description and not limitation.

The invention comprises a new method for increasing the lift of anairfoil, such as an aircraft wing, by (i) flexing the portion of thenose and bottom skin into the desired aerodynamical shape by a formingrib in the extended position, and by decreasing the lift by (2) flexingthe skin to the shape forming partly the nose and under surface of thewing when in retracted or normal airfoil position.

In order to fully disclose this invention so as to enable a personskilled in the art to carry out the same, it is deemed necessary todefine the flexible skin material as a non-metallic material such as aglass fiber resin or a metallic one such as aluminum or the like, or acombination of metal and fiber. A flexible material or a spring-typeresilient material or a memory retention type of material can beutilized, and many existing well known materials will be sufficient forobtaining the desired result.

Now, referring to FIGS. 1 and 2, there is illustrated a leading edgeflap mechanism which utilizes a forming rib 12 mounted about a pivotmeans 14 located forward and adjacent of the airfoil leading edge.

A skin portion 16 made from a memory retention material or a flexiblematerial as described is fixedly mounted along a spanwise airfoilportion 18 by fastener means 20 or the like.

From the fixedly mounted portion 18 the skin section 22 is unengaged anddisposes itself in a shape coincident with and part of the airfoilcross-sectional periphery. At the end of the unengaged skin section 22is a bracket 24 mounted to the skin 16 by fastener means 26 or the like.

In the retracted condition, FIG. 1, the flap mechanism 10, whichcomprises an actuating means 28, is stored within the nose wing interior30.

The actuating means 28 is unfolded by the power of an associated drivemeans (not shown) that rotates the axle 32 in the direction of the arrowand moves the following described components which are all part of theactuating means or mechanism 28. Thus, the mechanism 28 comprises theaxle 32, which is integrally connected to a bellcrank 34. The bellcrank34 contains two spaced-apart pivot points, a first pivot point 36 and asecond pivot point 38. The rib bracket 24 retains a third pivot point40, and the forming rib 12 employs a fourth pivot point 42.

A first linkage 46 interconnects the first pivot point 36 and the thirdpivot point 40 and a second linkage 48 interconnects the second pivotpoint 40 and fourth pivot point 42. Upon rotational actuation of theaxle 32 in the direction of the arrow, the bellcrank 34 will move thefirst linkage 46 which will move the skin section downwards from theairfoil interior 30 and away or unlock from a stop or installed snap-inmeans 50, located on the under-surface interior portion of the airfoil.Simultaneously the second linkage 48 will swing the forming rib means 12with its convex surface against the interior surface 62 of the skinsection 22 and pull that skin section 22 about the surface 60 in tightcontact relationship so that a smooth flowing curvature 7Q exists frompoint 72 to bracket 24, as shown in FIG. 2. The linkage 46 will stopfurther rotation as soon as full extension is achieved, and,accordingly, the over-center position of the linkages by means of theposition of pivot point 38 with respect to 42 and 40 will keep theleading edge flap thus formed by the contacting engagement of rib 12with skin section 22 in a locked extended position.

At the folded or retracted stage, the rib 12 may stop against the axle32 at the concave surface portion 80, or at the rib 12 end portion 84against the inside upper nose area 86.

Of course, it should be understood that those stop and/or snap-inretainer means such as stop 50 are optional and that various otherconfigurations can be designed for obtaining the same results.Furthermore, it should also be understood that the drive means (notshown) which rotates axle 32 may be removed and instead of driving axle32 one may drive or rotate the pivot means 14 and achieve similarresults. It can therefore be seen that various mechanisms or means forearrying out the unfolding and retracting of the rib 12 and skin 22 maybe devised which are all obvious to a person skilled in this art.

While one desirable embodiment of the invention has herein beendisclosed by way of example, it is to be understood that the inventionis not necessarily limited to this precise embodiment but is to beregarded as broadly inclusive of any and all equivalent constructionsfalling within the scope of the appended claims.

Now, therefore, I claim:

1. An airfoil leading edge flap mechanism comprising;

a. a nose skin section of resilient material forming part of saidairfoil; said section extending for a substantial predetermined portionfrom said airfoil nose area to said airfoil leading edge lower surfaceand being fixedly mounted to said airfoil nose area in a spanwisedirection while being unengaged from said fixedly mounted area to saidskin opposite end at said airfoil leading edge lower surface,

b. a forming rib means pivotally mounted within said airfoil nosesection adjacent said airfoil leading edge,

0. actuating means arranged within said airfoil nose for pivoting saidforming rib means in a downward forward direction and vice versa, forextension and retraction respectively;

d. said actuating means including a first linkage means mountedpivotally to said opposite skin end for keeping said skin section incontrolled curvature during said extension and retraction;

e. said actuating means including a second linkage means for moving saidrib means in downward forward direction about said rib means pivotalmounting, whereby said forming rib means upon extending rotation fromsaid airfoil nose section deforms said section into a desiredaerodynamic curvature for a highly cambered, high lift, low speed,airfoil, and

f. said actuating means including a pivotal mounted bellcrank meanshaving a pair of spaced-apart located pivot points carrying said firstand said second linkage means so that upon rotation of said bellcrank byan associated drive means said forming rib means and said skin sectionare positioned in coordination with one another in predeterminedrequired positions for said flap extension and retraction and wherebysaid pair of spaced locations are positioned to cause an over-centerposition of said linkage spaced pivotal points in said full extension sothat outside forces against said extended leading edge mechanism meet alocked structural extended position of said leading edge flap mechanism.

2. An aircraft leading edge flap mechanism for airfoils comprising;

a. an actuating mechanism driven by an associated driving means; saidactuating mechanism including; a bellcrank connected for rotation tosaid associated driving means; a forming rib means, a first and a secondlinkage each pivotally carried by said bellcrank;

b. said forming rib means pivotally mounted within said airfoil fordownward forward rotation about said pivotal mounting and vice versa;

0. a flexible skin section, covering at least partly said airfoil nosearea and said airfoil leading edge under-surface, fixedly mounted atsaid airfoil nose area and supportedly and pivotally mounted to saidfirst linkage at said skin section opposite end from said fixedlymounted nose area, and d. said second linkage means pivotally mountedwith said forming rib means so that upon actuation of said driving meanssaid bellcrank actuates said first and second linkages for moving saidskin section and said rib means respectively in said downward andforward position for forming said leading edge curvature, whereby saidforming rib means contacts said flexible skin section and deforms saidsection so that an airfoil extending leading edge curvature of increasedand desired high lift camber is achieved.

3. An aircraft leading edge flap mechanism for airfoils as claimed inclaim 2 wherein said first and second linkages are positioned inover-center locking arrangement so that said first linkage pulls saidflexible skin section in tight arrangement about said forming rib means.

4. An aircraft leading edge flap mechanism for airfoils as claimed inclaim 3 wherein said first linkage means is adapted, upon reverseactuation of said driving means, to retract said flexible skin sectionby said opposite end pivotally and supportedly arranged mounting means,so that said skin curvature becomes coincident with said basic airfoilperiphery supported by said first linkage mounting.

5. An aircraft wing improved airfoil leading edge flap mechanismmaintaining absolutely smooth nose leading edge surface curvature duringand at extended and retracted positions comprising a. actuator meansdriven by associated controlled driving means;

b. said actuator means including:

a bellcrank rotationally mounted within said airfoil nose section forreceiving said driving means force for rotation;

a first and a second elongated linkage means mounted each at one end andin spaced relationship with one another on said bellcrank;

a forming rib, having a desired low speed high camber curvature,pivotally mounted within said nose section next to said airfoil noseleading edge for pivoting downward and forward from and out of said nosesection for extension of said leading edge flap and vice versa forretraction of said leading edge flap and said forming rib pivotallyconnected to said first linkage other end for positioning said formingrib in said extension and retraction;

c. a skin section of flexible material fixedly mounted to said aircraftwing along a spanwise location on said airfoil upper nose leading edgeand disposed freely and coincidentally with said aircraft wing airfoilcontour from said fixedly mounted location until a predetermined areaapproximately at said airfoil leading edge lower surface end area andpivotally supported at said end area onto said second linkage meansother end, and

d. said first and said second elongated linkage means proportioned atpredetermined lengths so that upon rotation of said actuator means dueto controlled driving input by said driving means, said first linkagepushes said forming rib curvature against said flexible skin sectionduring extension and thereby said flexible skin is pulled about saidcurvature and is kept smooth and in tight condition by said secondlinkage holding said skin at said skin end area and whereby duringretraction said second linkage means positions said skin in its previousposition coincident with said aircraft wing airfoil contour.

6. An aircraft wing improved airfoil leading edge flap mechanism asclaimed in claim 5 wherein said aircraft wing at said predetermined areaapproximately at said airfoil leading edge lower surface end area isprovided with a mounted on stop holding means for assuring a correctlypositioned leading edge at retraction.

7. An aircraft wing improved airfoil leading edge flap mechanism asclaimed in claim 6 wherein said first and said second linkage meanspivotal mountings on said bellcrank in relationship with said mountingson said forming rib and said flexible skin end area provide for anover-center locking arrangement at said extended position of saidleading edge.

I l t I I

1. An airfoil leading edge flap mechanism comprising; a. a nose skinsection of resilient material forming part of said airfoil; said sectionextending for a substantial predetermined portion from said airfoil nosearea to said airfoil leading edge lower surface and being fixedlymounted to said airfoil nose area in a spanwise direction while beingunengaged from said fixedly mounted area to said skin opposite end atsaid airfoil leading edge lower surface, b. a forming rib meanspivotally mounted within said airfoil nose section adjacent said airfoilleading edge, c. actuating means arranged within said airfoil nose forpivoting said forming rib means in a downward forward direction and viceversa, for extension and retraction respectively; d. said actuatingmeans including a first linkage means mounted pivotally to said oppositeskin end for keeping said skin section in controlled curvature duringsaid extension and retraction; e. said actuating means including asecond linkage means for moving said rib means in downward forwarddirection about said rib means pivotal mounting, whereby said formingrib means upon extending rotation from said airfoil nose section deformssaid section into a desired aerodynamic curvature for a highly cambered,high lift, low speed, airfoil, and f. said actuating means including apivotal mounted bellcrank means having a pair of spaced-apart locatedpivot points carrying said first and said second linkage means so thatupon rotation of said bellcrank by an associated drive means saidforming rib means and said skin section are positioned in coordinationwith one another in predetermined required positions for said flapextension and retraction and whereby said pair of spaced locations arepositioned to cause an overcenter position of said linkages spacedpivotal points in said full extension so that outside forces againstsaid extended leading edge mechanism meet a locked structural extendedposition of said leading edge flap mechanism.
 2. An aircraft leadingedge flap mechanism for airfoils comprising; a. an actuating mechanismdriven by an associated driving means; said actuating mechanismincluding; a bellcrank connected for rotation to said associated drivingmeans; a forming rib means, a first and a second linkage each pivotallycarried by said bellcrank; b. said forming rib means pivotally mountedwithin said airfoil for downward forward rotation about said pivotalmounting and vice versa; c. a flexible skin section, covering at leastpartly said airfoil nose area and said airfoil leading edgeunder-surface, fixedly mounted at said airfoil nose area and supportedlyand pivotally mounted to said first linkage at said skin sectionopposite end from said fixedly mounted nose area, and d. said secondlinkage means pivotally mounted with said forming rib means so that uponactuation of said driving means said bellcrank actuates said first andsecond linkages for moving said skin section and said rib meansrespectively in said downward and forward position for forming saidleading edge curvature, whereby said forming rib means contacts saidflexible skin section and deforms said section so that an airfoilextending leading edge curvature of increased and desired high liftcamber is achieved.
 3. An aircraft leading edge flap mechanism forairfoils as claimed in claim 2 wherein said first and said secondlinkages are positioned in over-center locking arrangement so that saidfirst linkage pulls said flexible skin section in tight arrangementabout said forming rib means.
 4. An aircraft leading edge flap mechanismfor airfoils as claimed in claim 3 wherein said first linkage means isadapted, upon reverse actuation of said driving means, to retract saidflexible skin section by said opposite end pivotally and supportedlyarranged mounting means, so that said skin curvature becomes coincidentwith said basic airfoil periphery supported by said first linkagemounting.
 5. An aircraft wing improved airfoil leading edge flapmechanism maintaining absolutely smooth nose leading edge surfacecurvature during and at extended and retracted positions comprising a.actuator means driven by associated controlled driving means; b. saidactuator means including: a bellcrank rotationally mounted within saidairfoil nose section for receiving said driving means force forrotation; a first and a second elongated linkage means mounted each atone end and in spaced relationship with one another on said bellcrank; aforming rib, having a desired low speed high camber curvature, pivotallymounted within said nose section next to said airfoil nose leading edgefor pivoting downward and forward from and out of said nose section forextension of said leading edge flap and vice versa for retraction ofsaid leading edge flap and said forming rib pivotally connected to saidfirst linkage other end for positioning said forming rib in saidextension and retraction; c. a skin section of flexible material fixedlymounted to said aircraft wing along a spanwise location on said airfoilupper nose leading edge and disposed freely and coincidentally with saidaircraft wing airfoil contour from said fixedly mounted location until apredetermined area approximately at said airfoil leading edge lowersurface end area and pivotally supported at said end area onto saidsecond linkage means other end, and d. said first and said secondelongated linkage means proportioned at predetermined lengths so thatupon rotation of said actuator means due to controlled driving input bysaid driving means, said first linkage pushes said forming rib curvatureagainst said flexible skin section during extension and thereby saidflexible skin is pulled about said curvature and is kept smooth and intight condition by said second linkage holding said skin at said skinend area and whereby during retraction said second linkage meanspositions said skin in its previous position coincident with saidaircraft wing airfoil contour.
 6. An Aircraft wing improved airfoilleading edge flap mechanism as claimed in claim 5 wherein said aircraftwing at said predetermined area approximately at said airfoil leadingedge lower surface end area is provided with a mounted on stop holdingmeans for assuring a correctly positioned leading edge at retraction. 7.An aircraft wing improved airfoil leading edge flap mechanism as claimedin claim 6 wherein said first and said second linkage means pivotalmountings on said bellcrank in relationship with said pivotal mountingson said forming rib and said flexible skin end area provide for anover-center locking arrangement at said extended position of saidleading edge.